The present invention relates to a terminal device and, more particularly to a terminal device mounted on a terminal board for connecting wires for uses such as the output of electric power or signal. The present invention also relates to a crimp-style terminal for connected wires, ribbons or cables.
A terminal is any point on an element, component, device, etc. to which an element is attached. Conventional terminal devices typically have a terminal screw threaded into a fixed terminal strip. Conventionally, a wire is crimped between the head of the terminal screw and a surface of the fixed terminal strip.
Typically, the end of the wire is bent into a hooked shape that is positioned around the threaded shaft of the terminal screw. The terminal screw is then tightened to sandwich the wire between the screw head and the terminal strip surface. The connection is often unreliable because the wire can move, while the terminal screw is being tightened, so that the wire is not fully secured by the screw and surface.
Another source of unreliability is the poor crimping force exerted by conventional devices from their sandwiching a wire between the surface of the fixed terminal strip and the head of the terminal screw.
Another problem with conventional terminals is that the user, in trying to secure the wire, may overtighten the screw. Such overtightening can lead to the screw thread being stripped or to the wire being broken.
Another way users try to assure a good connection with conventional terminals is to form a full loop around the screw with the wire. Although this helps with the positioning of the wire, it makes disconnection of the wire difficult, particularly if the wire is of a heavy gauge.
Attempts to overcome the problems with the conventional screw and terminal surface connection include adding plain washers or star washers between the wire and the screw head or the terminal surface. These attempts do not fully overcome the problems of unreliability and difficulties in connecting and disconnecting.
Other attempts include using ratchet-like trap mechanisms in devices that, although they are easy to connect, are very difficult to disconnect. Often such mechanisms require cutting the wire to disconnect. Thus they can lead to disadvantageous shortening of the wire length.